1. Field of the Invention
The present invention relates to a display panel, and particularly relates to a touch panel.
2. Description of Related Art
At present, a display is one of the most popular among various consumers' optoelectronic products. As display technology advances, the use of displays is making our life more convenient than ever. Hence, the design of touch panels, especially, has become the representative of convenience. By directly touching the display frame, a user may utilize various functions of the touch panel, which simplifies the complexity of operating the touch panel.
Generally speaking, touch panels are categorized into two types, plug-in type and built-in type, according to the structures thereof. A built-in type product is usually thinner and lighter than a plug-in type product. Hence, built-in type touch panels are commonly applied in all kinds of portable electronic devices.
FIG. 1A is a cross-sectional view illustrating a portion of a conventional built-in touch panel. Referring to FIG. 1A, a built-in touch panel 100 includes a first substrate 110, a second substrate 120, a liquid crystal layer 140, a main spacer 150, a sensing spacer 160, an opposite electrode 170, a transparent conductive layer 182, a shielding layer 184, a plurality of color filter layers 184′, a protective layer 186, a first metal layer M1, a gate insulating layer GI′, an amorphous silicon layer AS, and a second metal layer M2.
The second substrate 120 is disposed opposite to the first substrate 110. The liquid crystal layer 140 and the main spacer 150 are arranged between the first substrate 110 and the second substrate 120. The sensing spacer 160 is disposed on the second substrate 120. The opposite electrode 170 is arranged on the first substrate 110 and corresponds to the sensing spacer 160, wherein the opposite electrode 170 is disposed on the protective layer 186 and contacts the protective layer 186. The transparent conductive layer 182 is disposed on the second substrate 120 and covers the main spacer 150 and the sensing spacer 160.
Generally speaking, the main spacer 150 and the sensing spacer 160 are formed by performing a photomask process, so as to simultaneously complete the fabrication of the main spacer 150 and the sensing spacer 160. However, because of the limitation of the photolithography process, the discrepancy between the height of the sensing spacer 160 and the height of the main spacer 150 is small or none.
Referring to FIG. 1A, when the built-in touch panel 100 is not touched, the shortest distance between the transparent conductive layer 182 covering the sensing spacer 160 and the opposite electrode 170 is a sensing gap g′. When the user touches the built-in touch panel 100, an electrical change is generated by the contact of the transparent conductive layer 182 covering the sensing spacer 160 and the opposite electrode 170. Thereby, the built-in touch panel 100 determines the area touched by the user.
In the conventional built-in touch panel 100, the sensing gap g′ remains the same or almost the same in every area. When the user touches an area having lower sensitivity, the user needs to apply larger stress so that the transparent conductive layer 182 on the sensing spacer 160 may contact the opposite electrode 170, i.e. to make the sensing gap g′ become 0. However, the transparent conductive layer 182 may be broken if the user applies excessive stress to the built-in touch panel 100, as indicated by the breaking position B1 and B2 in FIG. 1B.